Although the preparation of monomeric unsaturated mono- and difunctional compounds, such as mono- and dicarboxylic acid esters by an addition reaction of an olefin with a mono- or a dicarboxylic acid ester is well-known, as is taught in U.S. Pat. No. 3,783,136, it is difficult to regulate the attachment of the ester groups due to the nonselective character of the addition reaction.
Well-known methods for the preparation of polymeric unsaturated molecules with functional end groups have been by two ways: by ring-opening polymerization of cycloolefins with unsaturated organic diesters and by metathesis degradation of unsaturated polymer chains with unsaturated organic diesters. These methods have been used to prepare ester-group terminated certain average weight polyalkenes.
Linear alpha, omega difunctional polymeric compounds prepared by an olefin metathesis reaction have been prepared by ring-opening polymerization of cyclic olefins in the presence of unsaturated organic diesters or by metathesis degradation of unsaturated polymer chains in the presence of unsaturated organic diesters, but these methods have suffered from several disadvantages. It is difficult to prepare truly linear products without crosslinking and branching occurring, as is taught in U.S. Pat. No. 4,010,224, in an olefin metathesis reaction or an unsaturated polymer with cycloolefins. Also, as taught in U.S. Pat. No. 3,798,175, an olefin metathesis reaction of a cyclic olefin in the presence of an unsaturated carboxylic acid ester, the resulting polymers can contain a statistical distribution of repeating units. Random length molecular structures of random chain lengths therefore occur with attendant increased polydispersity.
As is well-known, side reactions can occur during olefin metathesis reactions. These side reactions include alkylation, isomerization, cyclization and addition across double bonds present in the molecular structure, resulting in cross-linked structures with non-linear characteristics. It has been found that the difunctional telechelic linear polyolefins of this invention prepared by olefin metathesis reactions wherein the functional groups are other than vinyl groups show little evidence of these side reactions in the preparation of these polyolefins. These polyolefins are true linear non-crosslinked polyolefins without pendant carbon groups as determined by nuclear magnetic resonance (NMR).